YES
(VAR x y z)
(RULES
f(i(x),x) -> e()
f(x,f(e(),y)) -> f(x,y)
f(e(),f(i(x),y)) -> f(i(x),y)
f(e(),i(x)) -> i(x)
i(f(x,y)) -> f(i(y),i(x))
f(x,f(y,i(y))) -> x
f(x,f(y,f(i(y),z))) -> f(x,z)
i(i(x)) -> f(e(),x)
i(e()) -> e()
f(i(x),f(x,y)) -> f(e(),y)
f(f(x,y),z) -> f(x,f(y,z))
f(x,e()) -> x
)